MARSHALL GATES
124
VOl. 66
Anal. Calcd. for ClnHsOIz: I, 60.15. Found: I , 60.07. Benzoylation of 3,5-Diiodo-4-hydroxybiphenyl.-The procedure used to prepare 3,5-diiod0-4-benzoxybiphenvl was the same as given above for the preparation-of 3-iodb4-benzoxydiphenyl. The product was recrystallized from ethanol. The resulting white needles melted at 159-160". Anal. Calcd. for C~sH120212: I, 4824. Found: I. -17.80. Attempted Triiodination of 4-Hydroxybipheny1,Severa1 attempts were made to prepare this compound in the manner described above for the mono- and diiodination of 4-hydroxybiphenyl by varying the solvent, the time of reaction and external heat applied. In each attempt, however, isolation of the desired product was unsuccessful.
\lowly turned yellow, the melting point falling to 92-93', The yellow samples upon analysis appeared t o have lost iodine. Calcd. for CitHsOTs: I, 57.86. Found: I, - -Anal. .a 33.lU.
The 3,5-diiodo-4-hydroxybiphenylset free from a sample of this ammonium salt gave white needles which readily decomposed. (b) ,Seventee11 grams of 4-hydroxybiphenyl was diszolved i n 40 ml. of glacial acetic acid. T o this mixture, 45 g. of iodine monochloride dissolved in 25 ml. of glacial acetic acid was added dropwise over a period of one-half hour. The mixture was then refluxed on a steam-bath for two hours. Hydrogen chloride gas was liberated freely during the reaction. After this treatment the mixture was cooled to room temperature and poured into a large volume of ice-water. A pale yellow solid and an oily, brown substance separated. Solid sodium bisulfite was added to the mixture in order to remove the iodine t o some extent. The water soluble constituents of the mixture were decanted and the remaining portion extracted with carbon tetrachloride. The carbon tetrachloride solution was washed with sodium bisulfite solution which removed the remaining iodine and was then washed with water and dried over anhydrous sodium sulfate. After the solution had dried, its volume was reduced to one-fourth the original volume by distillation under reduced pressure. Addition of petroleum ether to the remaining solution caused 21 g. of a white precipitate to separate. After dissolving the precipitate in chloroform and precipitating it from solution by the addition of petroleum ether several times and finally recrystallization from the mixed solvent of one-third chlorofonn and twothirds petroleum ether (b. p. 30-35:), the yield was reduced to 4 8 g The pure white solid melted at 86-87".
Summary 4-Hydroxybiphenyl has been mono- and diiodinated forming 3-iodo-4-hydroxybiphenyland 3,5-diiodo-4-hydroxybiphenyl, respectively. They were identified by analysis and analogy to the chlorination and bromination products of 4hydroxybiphenyl. Attempts to triiodinate 4-hydroxybiphenyl were unsuccessful. The benzoate derivatives of the above monoand diiodo-hydroxybiphenylshave been prepared, The mononitro derivative of 3-iodo-4-hydroxybiphenyl also has been obtained. NORMAN, OKLAHOMA AUSTIN, TEXAS
RECEIVEDOCTOBER1, 1943
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[CONTRIBUTION FROM
THE
MARIAN EDWARDS PARK LABORATORY OF B R Y K
MAWR COLLEGE]
The Condensation of Naphthoquinones with Polar Ethylenes BY MARSHALL GATES
In 1939 Wizinger and Coenen' showed that a carbon-carbon bond could be established by displacement of chlorine from polynitro aromatic chlorides using as displacing agents certain unsymmetrically substituted ethylenes. The ethylenes involved were of the type whose members readily form halochromic salts and show reactions with other types of electron acceptors. Their reactions indicate large contributions from forms in which the ethylenic link is polarized
sations of this type were found to take place with ease. To provide a trial free from the complicating side reactions which might be expected of benzoquinone, the action of 1,l-bis-(p-dimethylaminophenyl)-ethylene (I) on a-naphthoquinone was studied. On mixing these two reagents in benzene, acetone or dioxane, an intense deep purple color is produced immediately even a t room temperature, and on standing the solution deposits beautiful fine purple needles of 2-(1',4'-
CH:!
Since many of the reactions of quinones involve the addition of a molecule with an unshared electron pair to the conjugated system of the quinone, it might be expected that a carboncarbon bond could be established by the action of a polar ethylene of the above-mentioned type acting as an electron donor on a quinone acting as an electron accepting center. This expectation was fully realized and a number of conden(1) Wizinger and Coenen, J. p r a k f . Chcm., 1.58, 127 (1939) (2) Pfeiffer and Wiringer, A t f i r 461, 182 rIQ2R)
0
I1
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THE CONDENSATION OF NAPHTHOQUINONES WITH POLAR ETHYLENES
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thazarin diacetate gives V as an amorphous indigo-blue solid, m. p. 261-264", which can be hydrolyzed to IV with acid. The sparingly soluble 5,8-diacetoxy-l,4-naphthohydroquinone was isolated in 58% yield as the expected byproduct. Condensation of the desired type was not obtained using 2-methyl-l,4-naphthoquinone and I. A compound apparently derived from two moles of quinone and one of ethylene was obtained in low yield but its structure has not been established. The failure of 2-methyl-l,4-naphthoquinone to undergo easy condensation was not entirely unexpected since Fieser and Seligman3 showed that the presence of a methyl group in the quinonoid ring of 1,4-naphthoquinone 'materially reduces its ability to undergo 1,4-additions. Extension of this reaction to the preparation of condensation products of 1,l-dianisvlethvlene was successful-at G s t in the case of a-naphtho0 OH 0 quinone. In keeping with the less highly polar nature of this ethylene, as exhibited by its weaker proton affinity, condensation took place only slowly to give 2-(1',4'naphthoquinonyl-2')-1,1dianisylethylene (VI) as fine deep orange-red needles. An attempt to condense 1,l-dianisylethylene with 0-naphthoquinone in methanol failed to yield a condensation product containing the ethylene, but in addition to 8% of 2methoxy - 1,4 - naphthoquinone, gave rise to CHI-C' 43% of a high melting NO (275 ") hydroquinone, V VI CzHllOa, containing two naphthoquinonyl-4') - 1,l-bis - (# - dimethylamino- methoxyl groups. On methylation with dim'ethyl phenyl)-ethylene (111) as deep blue-black sulfate this gave the known4 3,4,3',4'-tetramethneedles (indigo blue in solution) in 83.7% yield. oxy-1,l'-binaphthyl. The hydroquinone can It was characterized as its deep red azine and as OH 0 its canary-yellow leucodiacetate. Other successful condensations using the same ethylene include those with naphthazarin and naphthazarin diacetate, leading to the related condensation products IV and V, respectively. Although poor yields were obtained in the case of the naphthazarin derivatives, purification losses were high and it is believed that the yields of pure material do not reflect the extent of conOH t; densation. The condensation product from naphVI1 VI11 thazarin crystallizes from benzene in beautiful black needles which exhibit a faint deep green (3) Fieser and Seligman,THISJOURNAL, OS, 2690 (1934). (4) Straw, Bunoully and Mautner, Ann., 444, 165 (1925). surface luster, m. p. 306-308' (uncor.). Naphnaphthoquinonyl-2') -1,l -bis- (p-dimethylaminophenyl)-ethylene (11). The best preparative procedure for this condensation product involves heating two molecular e uivalents of quinone with one of ethylene to 70B for twentyfour hours in dioxane. Under these conditions I1 separates in a directly pure condition in 59% yield, m. p. 271-272.5' (cor.). From the filtrate a-naphthohydroquinone, characterized as its diacetate and by oxidation to the starting quinone, was obtained in 95% yield (crude). The expected reaction course, in which the intermediate hydroquinone of I1 is oxidized to the quinone a t the expense of a molecule of starting quinone, is followed. The sparingly soluble condensation product I1 was characterized by analysis and by reductive acetylation to a greenish-yellow leucodiacetate. Using freshly prepared @-naphthoquinone,an even more facile condensation afforded 2-(1',2'-
1
MARSHALL GATES
126
probably be assigned the structure VII, since oxidation with silver oxide gave the hitherto unknown dimethyl ether of Stenhouse and Groves’sh “dinaphthyl diquinhydrone” as a deep magentacolored quinone, m. p. 260-262’ (VIII). The deep purple-black condensation product I1 derived from a-naphthoquinone and 1,l-bisjp-dimethylaminopheny1)-ethylenedissolves readily in 3 N hydrochloric acid to give a bright yellow solution. Dilution of this hydrochloric acid solution with a large volume of water causes the original quinone to separate as a purpleblack solid. The bright scarlet 3 N hydrochloric acid solution of I V likewise precipitates the original blue-black solid on strong dilution. These observations indicate that condensation of 1,l-bis-(p-dimethylaminophenyl)ethylenewith a-naphthoquinones results in a considerable decrease in basicity. An explanation of this is provided by a comparison of the structure of the free base with that of the cation formed by proton addition. Conjugation of the ethylene with a quinonoid nucleus increases the number of contributing forms of the free base considerably. and thereby increases the stabilizing resonance of the free base. Two of the possible forms are represented by formulas I1 and 1Ia.
I1 a
On the other hand, this increased resonance is not shown by the cation, in which the electron pairs responsible are tied up by covalent bond formation with the added proton or protons. This results in stabilization of the free base over the cation. The effect is greater in the condensation product than in the original ethylene and thus the condensation product is the weaker base. Formula IX represents a possible structure for the cation. Related to the above phenomena are the color changes which occur on solution of these condensation products- in moderately concentrated solutions of strong acids. Thus the deep purpleblack I1 gives a bright yellow solution, IV gives ( 5 ) Stenhouse and Groves, J Chem. Soc , 38, 418 (1878).
Vol. 66 I3 0
Apt - C I L I
\’
n
C’k”’
\
0 ‘%(CHa)2
0
!
H IX
a brilliant scarlet-red solution, and I11 (deep indigo blue) gives an orange-brown solution in 3 N hydrochloric acid. Since deep color is associated with the high electronic mobility of extensively conjugated systems to which many forms contribute,fi elimination of part of these contributing forms as shown above should lighten the color.’ Qualitatively, a t least, elimination of this resonance restores the color attributable to the original quinones alone, since a-naphthoquinone is bright yellow, naphthazarin is crimson, and pnaphthoquinone is golden-yellowto brown-yellow. Even the yellow to yellow-green leucodiacetates of I1 and I11 show this effect, both dissolving in dilute hydrochloric acid with complete loss of color which is restored by neutralization with bases. It is hoped to investigate these phenomena with the aid of absorption spectroscopy. Many condensations involving the union of an electron donating group with an accepting center are subject to catalysis by both acids and bases. The available evidence indicates that this is not the case with the condensation under discussion. Indeed, the reaction goes quite readily in aprotic solvents. Thus white preparative convenience dictates another choice of solvent the condensation between a-naphthoquinone and the ethylene I proceeds with ease in benzene. It might be predicted that acidic catalysis, operating by activating the electron accepting center, would fail because the electron donating ethylene is much more strongly basic than the accepting quinone in this case, and would be tied up as its inactive salt. This prediction is verified by the complete failure of the reaction to proceed when glacial acetic acid is used as solvent. Somewhat similar considerations indicate that basic catalysis is also unlikely. This type Qf catalysis, ordinarily effective because of proton capture from the electron donating component, cannot activate the donor in this case, since the donor is already basic and tends to gain rather than lose a proton. Experimentally it is found that even with the least basic ethylene examined (1,1-dianisylethylene), condensation with a-naphthoquinone goes with optimum yields when (6) Lewis and Calvin, Chcm. Reo., 2S, 273 (1939).
(7) Compare the cases of “reverse halochromism” described by Brooker, Sprague Srnyth and Lewis, THISJOURNAL, 62, 1116 ( 1940)
(8) For examples, see Hauser and co-workers, Abstracts ,Ninth National Organic Chemi-try Symposium, 1941, p 84.
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coding, 437 mg. of impure material, m. p. 175-179' with decomposition, was obtained. A second crop of 119 mg. was obtained from the filtrate; yield 95% (?de). Attempts t o recrystallize this material from dilute alcohol in the presence of a little stannous chloride and hydrochloric acid were unsuccessful. Accordingly, 177 mg. was dissolved in 1 ml. of pyridine and treated with 0.5 ml. of acetic anhydride. After standing two hours, the mixture was heated t o boiling and poured into water. The precipitated material was taken into ether, washed with dilute alkali several times, then with brine, filtered through anhydrous sulfate, and concentrated nearly to dryness. 0 The residue on crystallization from alcohol afforded 127 II mg. of light tan blades, m. p. 128-130". Recrystallization gave92 mg., m. p. 129-130'. Kom" records 128-130" for the m. p. of 1,4-diacetoxynaphthalene. The remainder of the material, dissolved in alcoholacetone, was treated with 1 g. of ferric chloride dissolved in dilute hydrochloric acid. A crop of orange-brown needles I i 0 CHs CH8 separated. These were collected, taken into ether, the ethereal solution treated with norite, filtered, concenXI X trated, and diluted with petroleum ether. A crop of acicThe relationship of this condensation product ular blades separated, 86 mg., m. p. 121.5-125'. After to the cyanine dyes is apparent. Other mem- recrystallization from ether, the material melted at 123.5bers of this series should be available by this 125.5' and did not depress the melting point of an authentic sample of a-naphthoquinone. condensation. The original orienting experiments on this condensa.An examination of the oxidation-reduction tion were carried out using benzene as a solvent. The conpotentials of these condensed quinones should densation takes place readily under these conditions but provide interesting data, and such detennina- the by-product a-naphthohydroquinone is sparingly soluble in this solvent and contaminates the product. It can also tions are to be made a t the earliest opportunity. be carried out in refluxing acetone t o give good yields. The interruption of this work for t$e duration However, the procedure given above yields the best product of the national emergency has prompted publica- and is preferred. The following describes an unsuccessful attempt t o tion of the present incomplete report. carry out the condensation using glacial acetic acid as a solvent. To the brilliant deep blue-green solution of 976 Experimental PartgJO mg. of 1,l-bis-(p-dimethylaminopheny1)-ethylene in 6 2-( 1',4'-Naphthoquinonyl-2') -1,l-bis-(p-dimethylamino- ml. of glacial acetic acid was added a warm solution of 1.16 phenyl)-ethylene (II).-A solution of 1.16 g. of a-naphtho- g. of a-naphthoquinone in 4 ml. of glacial acetic acid. quinone in 15 ml. of warm dioxane was added t o 0.973 g. Another 2 ml. of acid was used t o wash in the quinone. of l,l-bis-(p-dimethylaminophenyl)-ethylene11 dissolved The mixture was heated to 70' for sixty-seven hours, then in 15 ml. of the same solvent. A dark purple-red color allowed to cool. No crystalline material had deposited appeared immediately. The mixture, protected from light, after standing for twenty-four hours. The desired prodwas heated to 70' for twenty-three hours in a flask closed uct is very sparingly soluble in glacial acetic acid (74 mg. with a rubber stopper, then allowed t o cool for four hours. in 100 ml. at room temperature). The beautiful blue-black needles which had separated 2-( 1',4'-Diacetoxynaphthyl-2') -1,l-bis-(p-dimethylamwere collected and washed with cold dioxane; yield 906 inopheny1)-ethylene.-The condensation product I1 was mg. (5993, of directly pure material, m.p. 270.5-272'. acetylated as follows: 502 mg. of I1 dissolved The condensation product is very sparingly soluble in reductively in 10 ml. of hot pyridine was treated with 0.4 g. of zinc alcohol, acetone and glacial acetic acid, moderately soluble dust and 5 ml. of acetic anhydride. On addition of the in boiling dioxane with a deep purple-blue color. I t s solu- acetic anhydride the deep purple-black color changed to a tion in concentrated sulfuric acid is deep red-brown in light yellow-tan marked by an intense greenish fluorescolor, It dissolves in 3 N hydrochloric acid t o give a bright cence. yellow solution, which on strong dilution with water gives After standing ten minutes, the zinc was filtered off and k s t a greenish-yellow solution which then deposits the washed with ether, the filtrate diluted with ether, washed original material as a blue-black solid. A small portion three times with water, then three times with dilute alkali, was recrystallized twice from dioxane and dried at 78" once with water, finally with brine, and filtered through and 0.1 mm. for analysis, m.p. 272-273.5'. anhydrous sodium sulfate. The yellow solution thus obAnal. Calcd. for CzaH2602N2:C, 79.59; H, 6.20; N, tained had the same intense greenish fluoresence observed 6.63. Found: C, 79.45: H , 6.04; N, 6.72.Ia in t h e reaction mixture. After removal of the ether the The original dioxane filtrate was diluted with somewhat residual deep brown viscous oil on triturating under hexane more than an equal volume of water, then strongly acidi- solidified to a 9wn-yellow solid, 628 mg. (605 theoretical) fied with dilute hydrochloric acid. The dirty brown solu- m. p. 201-211 In contrast t o the starting quinone, this tion thus obtained was extracted twice with ether, the leucodiacetate crystallizes only with difficulty and pur& ether layers washed with dilute hydrochloric acid, satu- cation was costly. The crude material (550 mg.), dissolved rated brine, decolorized with norite, a t e r e d through an- in the minimal quantity of hot dioxane was treated with a hydrous sodium sulfate, concentrated and diluted with little hot water and allowed t o cool. The first crop sepa30-60" petroleum ether t o incipient crystallization. On rated as a glassy crust, 205 mg., m. p. 227-230", with decomposition. Dilution of the filtrate with alcohol gave (9) All melting points are corrected except those specifically de97 mg., m. p. 225-226", dec. These two crops were comscribed as uncorrected. bined, dissolved in the minimal quantitg of hot dioxane, (10) A preliminary condensation was carried out in collaboration diluted with an equal volume of hot alcohol and allowed t o with Mrs. Ray Longley. crystallize. The solution still showed an intense fluores(11) Pfeiffer and Wizinger, Zoc. cit. One crystallization from alcocence. Small compact prisms adhering t o the walls of the hol containing a trace of alkali yields an excellent product if the crude flask were obtained, 181 mg., m. p. 228-230" with decom-
no added basic catalyst (dimethylaniline) is present. It is planned to extend this work to other series of quinones and polar ethylenes, and a t least a start has been made in this direction. Thus with the expectation of obtaining XI, a-naphthoquinone has been condensed with N-methyl-Z-methylene-l,2-dihydroquinoline(X), although the condensation product has not been fully characterized
.
ethylene is subjected to preliminary vacuum distillation. (12) Semimicro Dumas analysis by Miss Gladys Whitridge.
(la) Kmm,Bn.,17, 3025 (1884).
128
M&sm.x,
position. Two further crystallizations gave small yellowtan prisms, m. p. 230-231' with decomposition. The m. p. depends somewhat on the rate of heating. For analysis the material was dried for three hours at 78' and 0.1 mm. It is sparingly soluble in alcohol, fairly soluble in acetone, and readily soluble in dioxane. I t s solution in concentrated sulfuric acid is orangered appearing canary-yellow to greenish-yellow in thin layers. It is soluble with complete loss of color in 3 N hydrochloric acid. Neutralization with dilute alkali gives a bright yellow precipitate of the unchanged leucodiacetate. Anal. Calcd. for Ca~Hs%O4N~: C, 75.56; H, 6.34. Found: C, 75.20; H, 6.23. 2-( I ',2'-Naphth uinonyl-4')-1,I-bis-(pdimethylaninophenyl)-ethylene ?HI).-To 2.32 g. of p-naphthoquinone'4 in 30 ml. of w a r n methanol was added a solution of 1.95 g. of 1,l-bis-(pdmethylaminopheny1)sthylene in 50 ml. of warm methanol. An immediate deep blue-green color was produced $khich on heating t o boiling rapidly gave way t o a deep indigo blue. At the end of a few minutes the product began t o separate as fine violet-black prismatic blades. The reaction mixture was allowed t o stand overnight at room temperature, then the product was collected and washed with cold methanol until the filtrate was clear blue with no reddish-purple tinge. After air drying, 2.58 g. (83.77J of material, m. p. 194-196' was obtained. It is rather sparingly soluble in methanol, fairly soluble in hot acetone and dioxane t o give deep indigo hlue solutions. Its solution in concentrated sulfuric acid is a deep ultramarine color. It dissolves in 3 N hydrochloric acid with a brown color. Dilution has no effect on this color, nor does it cause precipitation of the free base. A small sample was recrystallized twice from acetonemethanol, then dried at 100" and mm. for one hour, m. p. 199-201'. with gas evolution. AnaC. Calcd. for C m H ~ ~ O ~C, N 79.59; ~: H, 6.20; h', 6.63. Found: C, 79.40; H, 6.10; N,6.81.16 2-( 1 ',2'-Diacetolrynaphthy1-4')-I, I-bis-(p-dimethyhninopheny1)-ethylene.-To 630 mg. of the condensation product 111 suspended in 5 ml. of acetic anhydride was added 0.4 g. of zinc dust, then 10 ml. of pyridine. The deep blue suspension rapidly gave way t o a greenish-yellow fluorescent solution. After standing for fifteen minutes, the zinc dust was filtered off, washed with ether, then twice with hot pyridine, then again with ether. The light yellow iiltrate was diluted with water, the yellow ethereal layer was separated, washed three times with water and then extracted twice with dilute hydrochloric acid. The nearly colorless acid layer on neutralization with solid sodium bicarbonate yielded a canary-yellow solid. A third acid extract gave no precipitate on neutralization. After air drying, this precipitate amounted t o 738 mg. (97.4%),m.p. 95-102'. The material is sparingly soluble in cold methanol, readily soluble in benzene and chloroform. Its solution in hot acetone on cooling deposits the material as beautiful canary yellow needles, m. p. 92.594.5', but the yield on crystallization is poor. Successive crops afforded a total of 541 mg. (71.5%), m. p. 93-94'. To avoid prohibitive crystallization losses, a mixture of acetone-hexane was used for subsequent purification of an analytical sample. The material is obtained in partially solvated form from mixtures containing acetone. Thus a sample of the above material after two further crystallizations melted at 96-96.8",but after drying one hour at 78' and lo-* mm., the m. p. was raised t o 105.6106.8". It is soluble in concetltrated sulfuric acid with a deep orange-red color which changes t o red-purple on standing. It$solution in 3 N hydrochloric acid is colorless. Xeutralization precipitates t h e bright yellow solid. Anal. Calcd. for C&Is204Ne: C, 75.56; H, 6.34. Found: C, 75.59;H, 6.64. Azine of Condensation Product II1.-A solution of 619 mg. of 111 and 168 nig. of o-phenylenediamine in 10 ml. of benzene was treated with 1 ml of glacial acetic acid
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14) "Organic Syntheses," 11, 68 (1937). 1 5 ) Semimicro D u m a s analyais by Miss Mathilde Boa1
GATES
Vol. 66
On addition of the acetic acid and slight warming, the color changed from the original blue t o a deep red-brown. The mixture was heated under reflux for ten minutes, then diluted with an equal volume of hexane and set aside. Collection of the crystallizate afforded 645 mg. (89%) of deep red prismatic needles, m.p. 244-246', softening from 241'. Three further crystallizations of a small sample from benzene-hexane gave ruby-red blades, m. p. 246247.5". The azine is rather sparingly soluble in dcohol and acetone, readily soluble in hot acetic acid, hot dioxane or hot benzene. Its solution in concentrated sulfuric acid is a deep black-purple. It dissolves in 3 N hydrochloric acid with an orange color, and does not precipitate even on strong dilution. For analysis the material was dried at 78' and l W 4 mm. for one hour. Anal. Calcd. for Ca4HaNd: C, 82.56;H, 6.11. Found. C, 82.94;H, 6.15. Condensation of Naphthazarin with 1,l-Bis-( p d i methylaminophenyl) -ethylene (IV).-A solution of 190 mg of naphthazarin and 133 mg. of 1,l-bis-(p-dimethylaminophenyl)-ethylene in 15 ml. of benzene was brought t o boiling, then heated for twenty-four hours a t 74" in the dark. The resufting deep red-purple soIutidn was concentrated somewhat and set aside to crystallize. The crude materid1 which separated was collected and recrystallized from benzene t o give 54 mg. of black needles, m. p. 303-305" (uncor.). Recrystallization from hot benzene (deep bluepurple solution) gave 37 mg. of beautiful black needles with a faint deep green surface reflex, m. p. 306-308" (uncor.). I t s solution in concentrated sulfuric acid is a beautiful intense deep purple color. It dissolves in 3 A* hydrochloric acid with a deep crimson color, and on strong dilution separates out as a blue-black solid. A small amount suspended in alcohol (very sparingly soluble) gives a deep cornflower blue color on treatment with a drop of dilute alkali. The cornflower blue alkali salt thus formed is rather insoluble in water, but has some solubility in alcoholic solutions. The color produced is very similar to that produced when naphthazarin itself is treated with alkali. For analysis the material was dried a t 78" and mm. for one hour Anal. Calcd. for CzsH~04N2: C, 73.99; H, 5.77. Found: C, 74.27;H, 5.40. A larger run using dioxane as a solvent gave 233 mg. of crude material, m. p. 290-296' (uncor.), starting from 600 mg. of naphthazarin, but attempts t o purify this by solution first in diiute alcoholic alkali, then in dilute hydrochloric acid resulted in prohibitive losses, although a small amount of excellent material was obtained. Condensation of Naphthazarin Diacetate with 1,l-Bis(p-dimethylamlnophenyl) -ethylene (V) .-A solution of 402 mg. of naphthazarin diacetatele in 8 ml. of hot dioxane was treated with 192 mg. of 1,l-bis-(fi-dimethylaminophenyl)-ethylene in 2 ml. of dioxane and heated to 78" for ninety hours protected from light. The reaction mixture became brown immediately, then gradually darkened t o purple-red. Some very small well-formed colorless prisms separated along with some dark purple-red solid. The mixture of solids was filtered off (air dried, 286 mg.) and remystalkzed once from dioxane and once from ethyl alcohol to give 133 mg. of colorless prismatic plates of 5,sdiacetoxy- 1,4-naphthohydroquinone,17 m . p .249-250" The filtrate was diluted with water and the blue-black solid which precipitated was filtered off. In contrast to the other condensation products described, this material was not easily obtained in crystalline form. From its strongly concentrated dioxane solution only amorphous material separated (Bmg., m. p. 253-257'). Veryslowrecrystalliition of this material yielded amorphous material along with some needles. A further crystallization gave 80 mg. of blue-black amorphous material, m. p. 261-264". It is very sparingly soluble in alcohol, soluble in acetone, dioxane or benzene. I t s solution in sulfuric acid is a beautiful deep purple color. It dissolves in 3 N hydrochloric acid t o give a bright yellow solution which acquires a
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(16) Thiele and Winter, Ann., 311. 348 (1900). (17) Wheeler and Edwards. 'ram JOURNAL, 39, 2465 (1917).
Jan.,1944
THE CONDENSATION OF NAPHTHOQUINONES WITH POLAR ETHYLENES
greenish tinge on dilution but fails to precipitate. For analysis the material was dried at 78' and lo-' mm. for two hours. Anal. Calcd. for CsnHnOeNe: C, 71.36; H, 5.61. Found: C, 71.25; H, 5.23. The material is readily hydrolyzed t o the parent naphthazarin derivative as the following experiment shows. A solution of 42 mg. of crude condensation product (m. p. 250-255') in 3 ml. of dilute hydrochloric acid was heated t o boiling for five minutes. As the solution was heated, the color changed from yellow-green to deep crimson. The hydrolytic mixture was diluted with water, neutralized with solid sodium bicarbonate, the precipitated blue-black solid was taken into benzene, filtered, concentrated and set aside t o crystallize. Beautiful black needles of IV (20 mg.), m. p. 307-308" (uncor.), were obtained. Condensation of 2-Methyl-l,4-naphthoquinone with 1,I-Bis-(p-dimethylaminophenyl)-ethylene.-The reddish purple methanol solution of 645 mg. of 2-methyl-1,4naphthoquinone and 500 mg. of 1,l-bis-(p-dimethylaminophenyl)-ethylene was heated t o boiling, then allowed to stand at room temperature. A considerable portion of the ethylene separated on cooling. After standing in the dark without attention for one month, the original color had changed to a deep green and small nodules of dark crystalline material had separated. These were quite insoluble even in the boiling solvent, and on collection appeared greenish gray. The material was taken into dioxane to give a deep purple solution which on crystallization yielded 311 mg. of light tan platelets, m. p. 285-295" (uncor.). Two further crystallizations from dioxane gave 105 mg. of yellow plates which when introduced into a copper melting point block a t 290' melted at 298-300" (uncor.) after drying a t 78' and lo-' mm. for two hours. The melting point depends on the rate of heating. This material is soluble in dilute hydrochloric acid but is insoluble in alkali even on boiling. Its solution in concentrated sulfuric acid is a bright purple-blue which fades to a paler green-blue on standing. Analytical figures indicate that it is derived from two moles of quinone and one of ethylene. It has not been further characterized. Anal. Calcd. for CaHpuOdNz: C, 78.40; H, 6.58. Calcd. for CaHssOaNz: C, 78.66; H, 6.27. Found: C, 78.47; H, 6.57. 2 4 1',4'-Naphthoquinonyl-2 ') -1,l-dianisylethylene (VI), -A solution of 500 mg. of a-naphthoquinone and 38 mg. of l,l-dianisylethylene9 in 10 ml. of methanol was refluxed for: six days, when a small amount of the ethylene remained undissolved. After a day, the mixture had turned a dirty gray-green color and small amounts of bright orange fluffy solid could be discerned. At the end of the refluxing period the reaction mixture was filtered hot, the insoluble material washed thoroughly with hot methanol, then taken into hot benzene. After filtration to remove a small amount of dark green-brown material insoluble in benzene, the filtrate was diluted with hot methanol and allowed t o crystallize. Fluffy balls of very fine orange needles separated, 13,9 mg. (35% based on ethylene utilized), m. p. 209-210 A second crop of 18 mg., m. p. 208-210' was obtained from the filtrate; total yield 39.4%. Two further crystallizations from benzenemethanol gave 105 mg. ofofluffy balls of very fine orange needles, m. p. 211.8-212.3 . The substance is very sparingly soluble in methanol, readily soluble in hot benzene. Its solution in concentrated sulfuric acid is a deep blue to blue-green color. It is not soluble in dilute acids. The sample was dried at 78" and mm. for two hours for analysis. Anal. Calcd. for COeHzOO(: C, 78.77; H, 5.09; 2 OCHs, 15.66. Found: C, 78.85; H, 4.76; OCHs, 15.59. The original methanol filtrate on concentration and crystallization yielded 138 mg. of recovered ethylene as tan plates, m. p. 140-141.5". Earlier attempts to carry out this preparation in dioxane using anhydrous zinc chloride as a catalyst were unsuccessful, although the reaction was not heated so long as in the example given above.
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An effwt to speed up the condensation and improve the yield by use of dimethylaniline as a catalyst was likewise unsuccessful, although a small amount of the desired product was obtained. A description of this experiment follows : A mixture of 500 mg. of a-naphthoquinone, 380 mg. of 1,l-dianisylethylene, 4 drops of dimethylaniline and 25 ml. of methanol was heated in a closed pressure bottle at 78-80' for forty-eight hours. After cooling, the precipitated solid was filtered off and washed with methanol. The insoluble residue amounted to 257 mg. and contained particles of the characteristic orange condensation product. It was taken into boiling benzene, filtered from some dark gray-brown insoluble material (49 mg.) and diluted with an equal volume of hot methanol. The desired condensation product was obtained in poor condition as orange brown fluffs, 37 mg., m. p. 206.6-208", mixed m. p. with material obtained as above, 207-208.5". The filtrate from this crop on concentration and crystallization afforded 100 mg. of felty, fine ~ a y - t a nneedles, m. p. 136-139', which after two crystallizations from pure methanol formed nearly colorless plates, m. p. 141-141.5". A mixed m. p. with the starting ethylene was not depressed. The original methanol iiltrate on concentration and crystallization yielded 226 mg. of nearly black very impure material, m. p. 123-128", probably largely unchanged ethylene. Attempted Condensation of p-Naphthoquinone and 1,lDianisylethy1ene.-A solution of 1.00 g. of P-naphthoquinone and 760 mg. of 1,l-dianisylethylene in 30 ml. of methanol was heated to boiling and set aside in the dark. A part of the ethylene separated on cooling. After standing for one month, the solution was again heated to boiling. The ethylene dissolved, but considerable insoluble material remained. This was filtered off, dissolved in boiling dioxane to give a wine-red solution, and crystallized. Compact, red-brown prisms were obtained, 469 mg. (43% crude), m. p. 273-276'. While this material dissolved in boiling dioxane to give Ft deep wine-red solution, it was noticed that the refluxing solvent washed crystalline material adhering to the flask walls almost colorless. Therefore a small amount of stannous chloride dissolved in hydrochloric acid was added. This caused complete removal of the wine-red color, and after two crystallizations, 355 mg. of very pale pink prisms was obtained, m. p. 277.5278.8", becoming brown a degree or so below the melting point. One further recrystallization from dioxane containing stannous chloride and hydrochloric acid gave 313 mg. of nearly colorless material of the same melting point. Its solution in concentrated sulfuric acid was a very deep black to black green color. For analysis one sample was dried two hours a t 100' and 10-8 mm., and another sample was sublimed at 200" and 10-8 mm. Anal. Calcd. for CtzH;aO4: C, 76.27; H, 5.24; 2 OCHa, 17.92. Found: (crystallized sample) C, 76.18; H, 5.41. Found: (sublimed sample) C, 76.37; H , 5.24; OCH8, 17.41. Eighty-three mg. of this material was suspended in a small amount of potassium hydroxide solution containing some sodium hydrosulfite. Complete solution did not occur even after further dilution with water, but the hard prisms gave way to a very fine suspension. This suspension was treated with 0.2 ml. of dimethyl sulfate, stoppered, and vigorously shaken. The methylation was repeated, using additional dimethyl sulfate and more alkali. The agglomerated solid material was filtered off, washed with water, then with methanol, and crystallized from methanol. A considerable portion was lost accidentally, but the oremainder afforded 27 mg. of small plates, m. p. 145147 One further crystallization gave material melting at 146.5-148.5' which showed no depression in melting point when mixed with an authentic sample of 3,4,3',4'tetramethoxy-1,l'-binaphthyl' prepared by methylating a vatted sample of dinaphthyldiquinhydroneB with dimethyl sulfate. The original methanol filtrate on concentratio? yielded 428 mg. of unchanged ethylene, m. p. 139-141 , mixed m. p. 140.5-142'. The filtrate from this crystallization on
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K. E. RUNDLE,LESTERDAASCH AND DEXTERFRENCH
I30
standing deposited 147 mg. (8%) of brick-red material, m. p. 177-180.5”. Recrystallization from methanol with the aid of charcoal gave 109 mg. light yellow needles, m. p. 180.E1-18L.5~ whose mixed m. p. with an authentic sample of 2-methox~-1,4-naphthoquinone of m. p. 181.2-182° was 180.5-181.7 Oxidation of VI1.-A suspension of 40 mg. of VII, 200 ing. of silver oxide and some anhydrous magnesium sulfate in dioxane was warmed to facilitate solution. A brilliant deep magenta-purple was produced almost at once. After shaking for thirty minutes the suspension was heated to boiling and filtered. The deep magenta filtrate was concentrated to a small volume and set aside. An amorphous dark precipitate separated which was collected and washed with cold dioxane, yield 17 mg., m. p. 26C-262”. When held above its melting point for a few minutes, the beautiful deep red melt fades to a yellow-brown. The material when dry possesses a deep greenish-bronze surface reflex. i t s magenta-purple solution in dioxane on standing fades t o a brown solution. A small amount in dioxane on treatment with dilute aqueous alkali fades through a tan to a light green-yellow solution. It dissolves in concentrated sulfuric acid with a deep green-black color. For analysis, mm. for one the material was dried at 78” and
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hour.
[CONTRIBUTION FROM
THE
Vol. 66
Anal. Calcd. for CttH160,: C 76.73; H,4.68;2 OCHa. 18.02. Found: C,76.26; H, 4.79;OCHs, 16.33.
Summary 1. Condensation reactions between 1,l-bis(fi-dimethylaminopheny1)-ethyleneand a-naphthoquinone, 0-naphthoquinone, naphthazarin, and naphthazarin diacetate as well as a similar condensation between 1,l-dianisylethylene and CYnaphthoquinone have been described. 2. These condensations are those expected from a consideration of the electron donating capacity of the ethylene and the electron accepting capacity of the quinones involved. Present evidence indicates that the condensation is not catalyzed by acids or bases. 3. A discussion of certain points of interest in connection with the color and basicity of the condensation products is given. BRYNMAWR,PENNSYLVANIA RECEIVED SEPTEMBER 7, 1943
IOWA AGRICULTURAL EXPERIMENT STATION]
The Structure of the “B” Modification of Starch from Film and Fiber Diffraction Diagrams’ BY R. E. RUNDLE, LESTERDAASCH AND DEXTERFRENCH Introduction.-Of the unit cells proposed for the “A” (cereal) and “B” (tuber) modifications of a starch, those of Bear and French2 are supported by the best diffraction data, and are altogether the most reasonable thus far proposed. Yet even their data, as they point out, were necessarily confined to those available from powder diagrams. Such data are not wholly adequate for the support of large unit cells for crystals of low symmetry, so that their results are left open to question. Though the desirability of obtaining film and fiber diGraction diagrams for starch obvious, attempts to prepare suitable films and fibers have been unsuccessful because whole starch was employed. The chief constituent of whole starch3is a highly branched component, amylopectin in Meyer’s nomenclature, where interruptions in the starch chains occur approximately every 20 glucose residues. The resulting unbranched portions of the chains are too short to produce satisfactory films or fibers. Fortunately, it is now possible to isolate the unbranched (amylose) component present in most starches.’ The unbranched chains in this (1) Journal Paper No. J-1129of the Iowa Agricultural Experiment Station, Ames, Iowa. Project 639. Supported in part by a grant from the Corn Industries Research Foundation. (2) R. S. Bear and D. French, THIS JOURNAL, 68, 2298 (1941). (3) F.Bates, D.French and R. Rundle, ibid., 66, 142 (1943). (4) K. Meyer, “Advances in Colloid Science.” Interscience Publishers, Inc., New York, N.Y., 1942,pp. 142-162. ( 5 ) T J. Schoch, THIS JOURNAL, 64,2957(1942). For an analysls (of the compnnent iiolated hy Schoch, and a discussion of structure. (?I
component are probably in excess of 200 glucose units long,e and upon suitable treatment form both films and fibers. The production of these films and fibers and mention of the importance of their optical properties have been reported pre~iously.~ Recently Whistler and Hilbert have confirmed this property of amylose, finding that the acetate of this component of starch forms films with properties to be expected only for films of long, linear molecules.8 The diffraction diagrams from amylose retrograded at room temperature are quite like those from tuber starch granules and retrograded whole starch, so that the amylose component of starch can be used for the study of the crystalline portions of whole starch. Preparation of the Samples.-A hot solution containing about 5% amylose is allowed t o evaporate slowly, and the surface skins are removed carefully from time to time. The skins are allowed to dry on a n aluminum sheet or ferrotype. Dry films thus prepared are only a few hundredths of a millimeter thick. The thicker 61ms usually tend to curl or become distorted, but this can be overcome to some extent by doubling them while they are still wet. Fibers which produce a “B” diffraction diagram are very difficult t o prepare, and none that we have produced is of particularly high quality. The chief difficulty lies in the fact that plasticizers which can be used to aid in stretching produce fibers corresponding to new crystalline rnodificatiotis of starch. These, of course, are of interest in ( 6 ) J. Foster and R . Hixon, i b i d . , 65, 618 (1943). (7) R. Rundle and D . French, ibid., 66, 559 (1943).
(8)R. Whistler and G . Hilbert, “The Film-Forming Properties of the Acetates of Fractionated Starch.” read before the Division of Sugar Chemistry, Am. Chem. six. convention, Detroit, 1943.
